Hanging columns of plant-growing modules onto an existing wall is certainly the least expensive way to create tall hydroponic towers. The example house shown further above is tall enough to hang 32-foot tall towers (172 modules in 14 towers). Low wall height or wall-shading problems can be solved by building one or more masts to hang towers on. Each of the mast's 4 sides is a "wall" for hanging one tower.
It is easy and inexpensive to create a tall mast of any height by laminating a 3 x 3 matrix of standard 2" x 2" lumber as shown above. Using a table saw and construction adhesive, scrap wood can be glued together with staggered splice joints and the resulting mast can be anchored in concrete like a fence post. For larger scale operations, Figure 10 here and page 11 here explain how the mast can be rotated to optimize lighting of the plants growing on each of their towers.
The illustrated plant-growing modules are inexpensive "flower-pouch" bags that are well-suited to growing plants in an organic soil media. The image also portrays an efficient horticultural strategy. Notice that each plant-growing module is packed with (typically organic) soil and that a "back-channel" of highly permeable media (such as Perlite) is packed along the back side of it to act as a drain.
This module-drainage feature enables a high flow-rate to cascade through the many modules in a tall tower. Simply running a garden hose to the top of the very tall tower will enable irrigation of its large volume of organic growing media. If the flow of cascading water is limited to a trickle then a very cost effective constant-loss system can be implemented. Pumping hydroponic fluid back up the tower and cascading it through an inorganic growing media has some advantages however it would be considerably more costly. The goal and advantage of this invention is to achieve the lowest cost per unit volume of irrigated root mass.
An added benefit of using soil-based growing media is that produce grown in this soil-based tower can certified organic; that's something hydroponic growers cannot legally do. Hanging towers on the side of an existing house is cost-effective however many houses don't have a wall that is well-suited (due to shading or architectural concerns). Anchoring a free-standing tower-mast in concrete (like a flagpole) is one alternative but it too is subject to physical site limitations as well aesthetic reasons for homeowner reluctance. The freestanding "Cube Farms" illustrated above provide the greatest flexibility... they can be assembled on any flat surface so they are particularly well-suited to rooftop farming on large urban buildings.
Another very useful innovation is the "Drain-to-waste" methodology described in detail on page 8 in the application. The compost-tea brewing vat described on page 9 has perfect synergy with the tall towers.